Field of the Invention
This invention relates in general to photography and in particular to photographic elements provided with a magnetic recording region, such as a stripe or layer, that is useful for sound recording. More specifically, this invention relates to a method for forming a magnetic recording region on a photographic element in which a dispersion of finely-divided magnetic particles in a liquid medium is applied to the element in a predetermined form and the dispersion is solidified by bringing the element into contact with an induction-heating apparatus.
2. Description of the Prior Art
It is well known to form magnetic recording stripes on photographic elements, such as motion picture films, and a variety of procedures have been developed to accomplish this objective. The magnetic recording stripe can be applied to the image-forming side of a photographic element, for example, it can be applied within a narrow groove formed within a silver halide emulsion layer. Alternatively, the magnetic recording stripe can be applied directly to the support on the side opposite to the image-forming layer(s). When the photographic element is of the type which has an anti-halation layer on the side of the support opposite to the image-forming layer(s), the usual practice is to apply the magnetic recording stripe to that side of the support that carries the anti-halation layer. This can be done by removing the anti-halation layer locally before applying the stripe, as described in U.S. Pat. No. 3,050,758. Alternatively, it can be done by forming a magnetic striping composition which is capable of penetrating through the anti-halation layer to the support, as described in U.S. Pat. No. 3,220,843, or by applying a magnetic striping composition which reacts chemically with the binder of the anti-halation layer as described in U.S. Pat. No. 3,840,374.
It is a common procedure, in forming a magnetic recording stripe on a photographic element in accordance with the processes of the prior art, to dry the stripe in a drying chamber in which it is contacted with a hot gaseous medium, such as air that has been heated to an elevated temperature. This procedure suffers from many disadvantages; for example, it usually requires a very lengthy drying period with the result that the drying chambers must be of great length and, consequently, are very costly. Moreover, because of the long time and relatively high temperatures needed for drying, re-humidification chambers may be needed to replace moisture driven out of the photographic element during the drying operation. This adds greatly to the cost and complexity of the equipment. Also, in cases where a solvent incorporated in the striping composition is of high boiling point, the temperatures required to completely dry the stripe may be so high as to render it very difficult to avoid damage to the photographic element.
In addition to the application of magnetic recording stripes, it is also known to provide photographic elements with magnetic layers which can, if desired, be co-extensive in width with the image-forming layer(s) of the element. Photographic elements comprising such magnetic layers are disclosed in U.S. Pat. No. 3,782,947. As described in this patent, in this type of element the granularity of the magnetic recording medium is matched to the granularity of the photographic medium so that the magnetic recording medium is essentially transparent in a photographic sense. Thus, the photographic image can be viewed through the magnetic recording medium and the magnetic recording medium can be employed for recording and playback of information. Solidification of the magnetic recording medium in this type of element has also been carried out heretofore in drying chambers in which the element is contacted with a hot gaseous medium and suffers equally from the disadvantages described hereinabove with reference to the solidification of magnetic recording stripes.
It is toward the objective of providing an improved method for magnetic striping of photographic elements, or for the formation of magnetic recording layers or other magnetic recording regions, which eliminates the need for drying chambers utilizing a hot gaseous medium or enables such chambers to be of shorter length or to utilize lower temperatures, that the present invention is directed.